Epoxy resins are useful in many applications such as coatings, laminates, composites, adhesives, castings and the like. In each of these applications, it is desirable to have epoxy resins with an improvement in any one or more of their physical and/or thermal and/or chemical resistant properties.
The present invention provides a method for improving one or more of these properties by incorporating into the polymer chain of the epoxy resin one or more rodlike mesogenic structure(s). These epoxy resins exhibit ordering of the molecular chains in the melt phase and/or in the advanced compositions thereof. This morphology is susceptible to flow induced orientation during processing which can result in enhanced unidirectional, mechanical properties. This is not possible to any great extent with conventional epoxy resins.
In contrast to other types of mesogenic polymers, which are primarily thermoplastics, the epoxy resins containing rodlike mesogenic moieties provide an advantage in that final chain extension and/or crosslinking occurs during the curing stages of the fabricated part. This permits new systems which process at much lower temperatures.
The rodlike mesogenic structures incorporated into the chain provide the improvement in one or more of the properties. The property improvements obtained with epoxy resins of this type can be undirectionally enhanced by electric or magnetic fields or by shear stresses applied during processing and/or curing.